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Dinitrobenzene induces methemoglobin formation from deoxyhemoglobin in vitro
G B Vásquez1, G Reddy, G L Gilliland
1Center for Advanced Research in Biotechnology, National Institute of Standards and Technology, Rockville, MD 20850, USA.
Chemico-Biological Interactions
|May 19, 1995
Summary
Dinitrobenzenes convert deoxyhemoglobin to methemoglobin, but not oxy- or carboxyhemoglobin. This methemoglobin formation occurs without forming detectable hemoglobin adducts.
Area of Science:
- Biochemistry
- Toxicology
- Spectroscopy
Background:
- Hemoglobin (Hb) reactions with dinitrobenzenes (DNBs) are crucial for understanding toxicokinetics.
- Hemoglobin adducts serve as biomarkers for exposure.
- Methemoglobin (metHb) formation is a key outcome of Hb-DNB interactions.
Purpose of the Study:
- To elucidate the molecular mechanisms of hemoglobin reactions with dinitrobenzenes.
- To investigate the formation of methemoglobin and potential adducts.
- To enhance toxicokinetic models using Hb adducts as exposure biomarkers.
Main Methods:
- UV/VIS spectroscopy to monitor reactions with deoxy-(dxHb), oxy-(HbO2), and carboncarboxy-(HbCO) hemoglobin.
- High-Performance Liquid Chromatography (HPLC) with radiolabeled DNB to detect adducts.
- Spectral deconvolution and analysis of isobestic points.
Main Results:
- Dinitrobenzenes directly convert deoxyhemoglobin to methemoglobin.
- Minimal methemoglobin formation observed with oxy- or carbonboxyhemoglobin.
- No detectable covalent hemoglobin adducts were formed with deoxyhemoglobin.
- Methemoglobin formation is independent of adduct formation.
Conclusions:
- Dinitrobenzene reaction with hemoglobin is state-dependent, favoring deoxyhemoglobin.
- The reaction likely involves direct heme access or heme oxidation, more facile in the deoxy state.
- Methemoglobin formation is not directly linked to covalent adduct formation in this system.